I parked at the Glenfinnan train station (free). If you are planning on returning to your car by train it might be worth contacting them to see if you could leave your car there? On the OS map it's where the Hotel / Museum / Hostel and Candle Workshop is

It's also just off the A830 and west of a small car park that I chose not to park in (they were building / renovating houses just in front of it and there was a lot of big machinery pulling into the car park to do 3 point turns )... might that be the same small car park you're pondering on?

I think you have to assume that cars left overnight are not safe anywhere!!!!!!!!!!

Recently, driving back from Scotland, got pulled at a police roadcheck looking for gangs of East Europeans out of Glasgow that had been targeting cars parked overnight.

They advised when leaving your car anywhere that you leave no valuables and DEMOSTRATE that the car is empty by opening dash compartment and taking hatchback parcel shelf off showing nothing in the boot.

On my quest for munros I tend to go to Scotland for extended periods, I have to take a lot of gear for walking, climbing, camping, cycling and I am often forced to leave my car overnight in vunerable places.

My tactics are to use one of our mountaineering club huts as a base and go out for single/multiday trips. On single or multiday trips I only take minimum gear required for the specific objective(s) locking the rest up safely in the hut, have been demostrating what is in the car (usually nothing) when I leave it, for decades.

I then return back to my base for rest, wash clothes, cook some proper food, plan the next trip etc.

When I leave my MTB in the middle of nowhere, I remove the wheels, hide the frame, then hide each wheel in seperate places in the first 200m along my route.

When I go off for a multiple-day hike my car is full of base camp equipment and clothing etc. I have the back seats folded down to accommodate it all, but it is hidden under an old double duvet cover.My practice is to leave my car overnight in the middle of a village, in front of houses where the curtain-twitchers will be sure to keep an eye on it. Even better is if you see one of the householders in their garden or something, then you can ask with an air of innocence, Will my car be alright here for 2-3 days? I've also found that the smaller, quieter campsites will usually let you leave your car there if you ask them nicely, though the bigger sites tend to want to charge you per night for it.